1. Field of the Invention
The present invention relates to an optical fiber and an optical fiber cable interiorly providing such an optical fiber. Further the present invention relates to a radiation detecting system for monitoring radiation leak, using such an optical fiber and an optical fiber cable.
2. Prior Art
In facilities where radiation is handled or utilized, radiation leak causes a serious damage to human body. Thus various measures are taken in bar of these matter. In the unlikely event that the radiation leak occurs, some detecting system for quickly and reliably detecting this has been developed and has also come into practical use.
For example, a monitoring system, in which radiation-monitoring apparatuses such as well-known scintillometers are located at all of areas where the radiation leak potentially occurs to monitor the radiation leak all the time, has been established and used.
Since such conventional radiation-monitoring system presupposes to locate the scintillometer at each detection area and additionally the scintillometer is expensive, significant cost is necessary to construct such monitoring system. Under the circumstance usually having budget control, it may happen that the monitoring apparatuses cannot adequately be located at all of required areas. In this case, since the monitoring system does not cover every potential leak areas, it is desired to improve this defect. That is, it is eagerly desired to develop a new detecting device and an improved radiation-detecting apparatus adequately to detect the radiation leak.
The present invention has been developed in view of aforementioned circumstances. One object of the present invention is to provide an optical fiber and an optical fiber cable at a low cost. Another object of the present invention is to provide a radiation detecting system for detecting the radiation leak at a low cost.
For solving the aforementioned problem and achieving the object, in the first aspect according to the present invention, an optical fiber comprises a core having lightwave guide property and extending along one direction, a clad layer covering over a peripheral surface of the core to make a light transmitted in the core shield within the core, a scintillator material dispersed in the clad layer and emitting light when radiation is applied, wherein at least a part of the light emitted when radiation is applied to the scintillator material is transmitted within the core.
In second aspect according to the present invention, an optical fiber comprises a core having lightwave guide property and extending along one direction, a clad layer covering over a peripheral surface of the core to make a light transmitted in the core shield within the core, a detecting layer covering over a peripheral surface of the clad layer and a scintillator material dispersed in the detecting layer and emitting light when radiation is applied, wherein at least a part of the light emitted when radiation is applied to the scintillator material is transmitted through the clad layer and within the core.
In the first or second aspect, the scintillator material may be inorganic scintillator material. The radiation may also be at least one radiation selected from the group consisting of X-ray, xcex1-ray, xcex2-ray, and xcex3-ray, and the scintillator material may be emitted when any of X-ray, xcex1-ray, xcex2-ray, and xcex3-ray is applied.
In the first aspect, the optical fiber may further include a protective layer adapted to cover a peripheral surface of the clad layer. The core may be formed of quartz glass. The clad layer may be formed of transparent polymer synthetic resin. The scintillator material may also be dispersed in the clad layer by way of dope.
In second aspect, a protective layer may be adapted to cover a peripheral surface of the detecting layer. The scintillator material may be dispersed in the detecting layer by way of dope.
Further, in third aspect according to the present invention, an optical fiber cable comprises: an optical fiber including; a core having lightwave guide property and extending along one direction; a clad layer covering over a peripheral surface of the core to make a light transmitted in the core shield within the core; and a scintillator material dispersed in the clad layer and emitting light when radiation is applied, a radiation-shielding layer covering substantially over a periphery of the optical fiber, and a gap located in at least one part of the radiation-shielding layer to enable radiation to be entered into the clad layer.
Further, in fourth aspect according to the present invention, an optical fiber cable comprises: an optical fiber including; a core having lightwave guide property and extending along one direction; a clad layer covering over a peripheral surface of the core to make a light transmitted in the core shield within the core; a detecting layer covering over a peripheral surface of the clad layer; and a scintillator material dispersed in the detecting layer and emitting light when radiation is applied, a radiation-shielding layer covering substantially over a periphery of the optical fiber, and a gap located in at least one part of the radiation-shielding layer to enable radiation to be entered into the detecting layer.
In the third or fourth aspect, the optical fiber may further include a reinforcing layer adapted to cover a peripheral surface of the optical fiber. In addition, this protective layer may include bunch of reinforcing fiber extending along the one direction. Further, this reinforcing fiber may be secured on a periphery of the optical fiber with a tape winded around a periphery of the bunch of reinforcing fiber.
Further, in the third or fourth aspect, the optical fiber may further include a reinforcing layer adapted to cover a peripheral surface of the optical fiber, and the radiation-shielding layer may be adapted to cover a peripheral surface of the reinforcing layer. In addition, the tape may be coated with lead.
Further, in the third or fourth aspect, the gap may be formed over the entire length in the circumferential direction of the optical fiber. Otherwise, the gap may be formed in plural parts of the radiation-shielding layer along the one direction with a predetermined space.
Further, in the third or fourth aspect, the optical fiber cable may further include a radiotransparant tegumentary layer adapted to cover over a periphery of the radiation-shielding layer with locating as the most outer layer.
In fifth aspect according to the present invention, a radiation detecting system comprises an optical fiber cable adapted to emit light at a region where radiation is applied and transmitting the emitted light, photoelectric conversion means connected to at least one end of the optical fiber cable, and processing means detecting when radiation is applied in accordance with an output signal of the photoelectric conversion means.
In the fifth aspect, the radiation detecting system may further include an A/D conversion means between the photoelectric conversion means and the processing means to digitize the output signal. The photoelectric conversion means may include one input terminal to which one end of the optical fiber cable is connected. In addition, the optical fiber cable may further include a reflection means at another end of the optical fiber cable. Otherwise, another end of the optical fiber cable is opened.
Further, in the fifth aspect, photoelectric conversion means may include two input terminals to which both ends of the optical fiber cable are respectively connected.
Further, in the fifth aspect, the optical fiber cable may further include at least one detect portion, wherein the light emitted at the detect portion when radiation is applied to the detect portion is transmitted within the optical fiber cable. In addition, as first preferable configuration, the optical fiber cable may further include: an optical fiber having; an optical transmission core extending along one direction to transmit light emitted at the detect portion; a clad layer covering over a peripheral surface of the core; and a scintillator material dispersed in the clad layer and emitting light when radiation is applied, a radiation-shielding layer covering substantially over a periphery of the optical fiber, wherein a gap is provided with locating in at least one part of the radiation-shielding layer as the detect portion. Otherwise, as second preferable configuration, the optical fiber cable may further include: an optical fiber having; an lightwave guide core extending along one direction to transmit light emitted at the detect portion; a clad layer covering over a peripheral surface of the core to make a light transmitted in the core shield within the core; a detecting layer covering over a peripheral surface of the clad layer, a scintillator material dispersed in the detecting layer and emitting light when radiation is applied, and a radiation-shielding layer covering substantially over a periphery of the optical fiber, wherein a gap is provided with locating in at least one part of the radiation-shielding layer as the detect portion.
In these two preferable configurations, the optical fiber cable may further include a reinforcing layer adapted to cover a peripheral surface of the optical fiber, and the radiation-shielding layer may also include bunch of reinforcing fiber extending along the one direction. Further, this reinforcing fiber may be secured on a periphery of the optical fiber with a tape winded around a periphery of the bunch of reinforcing fiber.
In the first or second configuration, the radiation-shielding layer may be adapted to cover a peripheral surface of the reinforcing layer. In addition, the radiation-shielding layer may be formed by winding a tape coated with lead.
Further, in the first or second configuration, the gap may be formed over the entire length in the circumferential direction of the optical fiber. Otherwise, the gap may be formed in plural parts of the radiation-shielding layer along the one direction with a predetermined space.
Furthermore, in the first or second configuration, the optical fiber cable may further include a radiotransparant tegumentary layer may be adapted to cover over a periphery of the radiation-shielding layer with locating as the most outer layer. The scintillator material may also be inorganic scintillator material.
In the first configuration, the scintillator material may be dispersed in the clad layer by way of dope. In the second configuration, the scintillator material may be dispersed in the detecting layer by way of dope.
In the first or second configuration, the radiation may also be at least one radiation selected from the group consisting of X-ray, xcex1-ray, xcex2-ray, and xcex3-ray, and the scintillator material may be emitted when any of X-ray, xcex1-ray, xcex2-ray and xcex3-ray is applied.
In the first configuration, the optical fiber cable may further include a protective layer adapted to cover a peripheral surface of the clad layer. In the second configuration, the optical fiber cable may further include a protective layer adapted to cover a peripheral surface of the detecting layer.
Further, in the first or second configuration, the core may be formed of quartz glass. The clad layer may also be formed of transparent polymer synthetic resin.